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United States Patent ATES OR BENZONITRILE AND BRIGHTENING THEREWITH Annemarie Wagner and Siegfried Petersen, Leverkuse'n, Germany, assignors to Farhenfabrilren Bayer Aktiengesellschaft, Leverkusen, Germany, acorporation of Germany No Drawing. Application October 8, 1956 Serial No. 614,379

more particularly it concerns a method of brightening materials of various kind with colourless or nearly colourless fluorescent arylpyrazoline compounds of the general formula Ar-ccrnH ll 6/ COOH wherein Ar denotes an aryl radical, such as phenyl or napthyl, and X denotes hydrogen or an aryl radical. The arylpyrazoline compounds to be used as brightening agents according to the invention include those compounds which are further substituted in the aromatic nuclei of the above formula, for example by a further carboxyl group, halogen, low-molecular weight alkyl groups, hydroxyl-, alkoxy-, aminoor acylamino groups, as well as the functional derivatives of these compounds, such as eg their salts, esters, amides or nitriles.

The arylpyrazoline compounds proposed as brightening agents can be produced in various ways, for example, by the action of arylhydrazines containing carboxyl groups upon w-dialkylaminoaryl ketones, vinylaryl ketones, such as eg benzalacetophenone, or upon the salts of aminoethylaryl ketones.

The brightening agents of the present invention may be applied in the usual manner, for example, from an aqueous solution or dispersion at room temperature or at elevated temperature. The agents in the form of their alkali metal salts are generally soluble in an aqueous neutral or alkaline mediumbrightening agents Which are not capable of forming water-soluble salts are advantageously used with the aid of dispersing agents. The same is true for the use of the brightening agents in acid medium. They may also be used together with detergents.

The arylpyrazoline compounds proposed may be used for a great variety of materials, eg for brightening tex- 2,879,174 Patented Mar. 24, 1959 "ice - 2 brightened articles of synthetic polycondensates according to the process of co-pending application Serial No. 602,505, filed August 7, 1956, by Robert Schnegg, Erich Istel and Heinrich Gold which application is assigned to the same assignee.

The required quantities of the brightening agents to be used can be readily established in each case by preliminary experiments; in general, quantities of about 0.01--0.1 percent by weight are sufficient.

The following examples serve to illustrate the invention without, however, limiting the scope thereof; the

part given are by weight.

Example 1 0.005 parts of the sodium salt of 1-p-carboxyphenyl-3- phenylpyrazoline and 0.005 part of anhydrous soda are dissolved in water, the solution obtained is then treated with 0.2 part of a surface-active paraflin sulfonate and 0.2 part of acetic acid, and made up of 400 parts with water. Thereupon, 10 parts of polyacrylonitrile fibres are introduced into the solution, the bath is then heated to C. in the course of 20-30 minutes and-kept at this temperature for 1 hour. Subsequently the material is rinsed and dried. The brightening effect obtained is surprisingly good and has a comparatively high fastness to light having approximately an action four-times greater than that of the compounds known as brightening agents such as 1,3-diphenylpyrazoline or l-p-sulfophenyl- S-phenylpyrazoline.

A good brightening etfect is also obtained by treating the polyacrylo-nitrile fibres with the sodium salt of 1-p-carboxyphenyl-3-phenylpyrazoline in a neutral medium or by using instead of the salt the free acidor its ethyl ester. The salt, the free acid or its ethyl ester are obtainable in the following manner:

parts of acetophenone, 55 parts of ammonium chloride and 150 parts of 30% formaldehyde are heated with stirring under reflux on the water bath for 1 hour. Thereupon the lower layer is separated and heated to boiling with a solution of 152'parts of p-hydrazinobenzoic acid hydrochloride and 204 parts of anhydrous sodium carbonate in 1400 parts of water while stirring for 3 hours. The sodium salt of 1-p-carboxyphenyl-3- phenylpyrazoline is then precipitated. By the addition of hydrochloric acid to the suspension of the sodium salt in water the free acid can be obtained which has a melting point of 244C.

For the production of the ethyl ester parts of the salt or the free acid are suspended in 750 parts of ethyl alcohol and slowly mixed with 75 parts of thionyl chloride at 3040C. After boiling the reaction mixture under reflux for about 7 hours, the hot solution is filtered. From the filtrate the ethyl ester crystallizes and, after recrystallization from alcohol, has a melting point of 112C.

A similar brightening effect is obtained by applying l-p-cyano-3-p-chlorophenylpyrazoline; this brightening agent can be produced by heating a solution of equal molecular parts of p-cyanophenylhydrazine and p-chlorophenyl-fi-chloroethylketone in methanol for 2 hours under reflux in the presence of an acid-binding agent, such as pyridine or ammoniumcarbonate; the 1-p-cyano-3-pchlorophenylpyrazoline has a melting point of 183C.

Example 2 To a soap having a total fatty acid content of 60 percent, there are added with heating and good stirring 15 grams of 1-p-carboxyphenyl-3-phenylpyrazoline per 100 kilograms, preferably in the form of a suspension in a soap solution. The resulting soap is excellently brightened.

, r o i 7 x l 3 To a soap base containing 80 percent of fatty acid, such as is generally used for the production of toilet soap there are added with stirring in the mixer prior to the milling machine l0 '30 grams of l-p-carboxyphenyl-ia'a p-chlorophenylpyrazoline per 100 kilograms, expediently in-the form'of a suspension in a soap solution or in an cmulsifienif desired together with the conventional additives such as perfume, dyes, white pigments and deodorants. The non-coloured toilet soaps present a purewhite appearance; in coloured soaps the shades of colour become more brilliant.. i

l-p-carboxyphenyl-B-pchlorophenylpyrazoline can be prepared in the following manner: 1 54 parts of fi-chloropropionic acid are heated on the water bath with 77.5 parts of ,thionyl chloride for 1% hours with the exclusion of water. Thereupon the reaction mixture is added to a mixture of 81 parts of aluminum chloride and 170 parts of dry chlorobenzene. After standing for 24 hours the mixture is poured onto a mixture of ice and hydrochloric acid. Then the chlorobenzene layer is separated and refluxed with 95 parts of p-hydrazinobenzoic acid and hydrochloride, 80 parts of pyridine and 750 parts of methanol for 2 hours. The 1-p-carboxyphenyl-3-p-chlorophenylpyrazoline obtained has a melting point of 270272C.

Example 4 10-30 grams of l-p-carboxyphenyl 3-phenylpyrazoline are incorporated" with 100 kilograms of a soap base suitabletor soap flakes in a mixing apparatus prior to the working up in the milling machine. The soap flakes obtained by conventional processing are outstandingly brightened. Linen having been washed with these soap flakes alsoshow a very good brightening efiect.

' We claim: 1 v t I 1. Aprocess for brightening materials which comprises applying thereto a fluorescent arylpyrazoline compound of the general formula wherein Z is a member of the group consisting f of COOH, a neutralized carboxyl group, COOR where R is lower alkyl, and cyano; and X is a member selected from the group consisting of hydrogen and chloro."

2. A compound of the general formula Y References Cited in the file of this patent 1,640,056 Kendall et a1. May 26; 1953 

1. A PROCESS FOR BRIGHTENING MATERIALS WHICH COMPRISES APPLYING THERETO A FLUORESCENT ARYLPYRAZOLINE COMPOUND OF THE GENERAL FORMULA
 2. A COMPOUND OF THE GENERAL FORMULA 